A penalty by fly half Lewis Williams five minutes from time proved crucial as Cardiff Blues Under 18s sneaked home 6-5 against Leinster at the Arms Park.
Lewis had given the home side a narrow 3-0 lead at the break in a keenly contested affair with a well struck penalty in the 10th minute.
Leinster looked like they had burgled the game with a 70th minute try through flying winger mark Roche but Williams showed nerves of steal to secure the win for the Blues.
The Blues pack proved extremely industrious with prop Lewis Smout, hooker Jack Dando and backrow Ellis Jenkins making their presence felt with sterling performances.
